PHP图片处理与GD库使用教程

<?php
function resizeImage($sourcePath, $targetPath, $maxWidth = 800) {
    // 检查文件是否存在
    if (!file_exists($sourcePath)) {
        die("源图片不存在：$sourcePath\n");
    }
<pre class="brush:php;toolbar:false;">// 获取图片信息
list($width, $height, $type) = getimagesize($sourcePath);

// 计算新尺寸
if ($width &lt;= $maxWidth) {
    copy($sourcePath, $targetPath);
    echo "图片无需缩放，已复制。\n";
    return;
}

$ratio = $maxWidth / $width;
$newWidth = $maxWidth;
$newHeight = intval($height * $ratio);

// 创建源图像资源
switch ($type) {
    case IMAGETYPE_JPEG:
        $srcImg = imagecreatefromjpeg($sourcePath);
        break;
    case IMAGETYPE_PNG:
        $srcImg = imagecreatefrompng($sourcePath);
        break;
    default:
        die("不支持的图片格式\n");
}

// 创建目标图像资源
$dstImg = imagecreatetruecolor($newWidth, $newHeight);
imagecopyresampled($dstImg, $srcImg, 0, 0, 0, 0, $newWidth, $newHeight, $width, $height);

// 保存结果
imagejpeg($dstImg, $targetPath, 90);
imagedestroy($srcImg);
imagedestroy($dstImg);

echo "图片已缩放并保存至：$targetPath\n";

}

// 命令行参数处理 if ($argc < 3) { echo "用法：php resize.php <源图片> <目标图片> [最大宽度]\n"; exit(1); }

$source = $argv[1]; $target = $argv[2]; $maxWidth = isset($argv[3]) ? (int)$argv[3] : 800;

resizeImage($source, $target, $maxWidth); ?>

// 在原函数基础上扩展水印功能
function addWatermark($imagePath, $text = 'Copyright') {
    $img = imagecreatefromjpeg($imagePath);
    $color = imagecolorallocatealpha($img, 255, 255, 255, 70); // 半透明白色
    $fontFile = '/path/to/arial.ttf'; // 系统字体路径
<pre class="brush:php;toolbar:false;">$fontSize = 20;
$bbox = imagettfbbox($fontSize, 0, $fontFile, $text);
$textWidth = $bbox[2] - $bbox[0];
$textHeight = $bbox[7] - $bbox[1];

$x = imagesx($img) - $textWidth - 20;
$y = imagesy($img) - $textHeight - 20;

imagettftext($img, $fontSize, 0, $x, $y, $color, $fontFile, $text);
imagejpeg($img, $imagePath, 90); // 覆盖原图或另存
imagedestroy($img);

}

#!/bin/bash
for file in *.jpg; do
    php resize.php "$file" "thumb_$file" 500
done